19864981 has 2 divisors, whose sum is σ = 19864982. Its totient is φ = 19864980.

The previous prime is 19864961. The next prime is 19864987. The reversal of 19864981 is 18946891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19847025 + 17956 = 4455^2 + 134^2 .

It is a cyclic number.

It is not a de Polignac number, because 19864981 - 2¹¹ = 19862933 is a prime.

It is a super-2 number, since 2×19864981² = 789234940260722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19864987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9932490 + 9932491.

It is an arithmetic number, because the mean of its divisors is an integer number (9932491).

Almost surely, 2^19864981 is an apocalyptic number.

It is an amenable number.

19864981 is a deficient number, since it is larger than the sum of its proper divisors (1).

19864981 is an equidigital number, since it uses as much as digits as its factorization.

19864981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 124416, while the sum is 46.

The square root of 19864981 is about 4457.0148081423. The cubic root of 19864981 is about 270.8295519998.

The spelling of 19864981 in words is "nineteen million, eight hundred sixty-four thousand, nine hundred eighty-one".